microaneurysmA weakened area in the walls of tiny blood vessels. In diabetic retinopathy, microaneurysms can occur in the retina from damage related to abnormally high blood sugar levels. As microaneurysms in tiny blood vessels (capillaries) expand, ruptures can result. These ruptures lead to hampered blood flow as well as swelling and leakage that sometimes cause scarring, blind spots and blindness.